73 lines
1.6 KiB
Python
73 lines
1.6 KiB
Python
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import sys
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from collections import defaultdict
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map = [list(x.strip()) for x in sys.stdin]
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print(map)
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Y = len(map)
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X = len(map[0])
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assert all(len(row) == X for row in map)
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N,E,S,W = 1,2,4,8
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unknown = 0b11111
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grid = {}
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start = None
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for i, row in enumerate(map):
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for j,c in enumerate(row):
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d = 0
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if c == ".": d = 0
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elif c == "7": d = W|S
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elif c == "J": d = N|W
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elif c == "L": d = N|E
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elif c == "F": d = S|E
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elif c == "|": d = N|S
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elif c == "-": d = W|E
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elif c == "S":
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d = unknown
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start = (i,j)
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else:
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raise Exception("invalid char %s at (%s,%s)" % (c, i, j))
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grid[i,j] = d
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print(grid)
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def find_loop(grid, start):
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front = [(0,start)]
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dist = {}
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count = defaultdict(int)
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count[start] -= 1
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def push(i,j,from_):
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if grid.get((i,j),0)&from_:
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front.append((cost+1, (i,j)))
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while front:
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front.sort()
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cost, n = front.pop(0)
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if n not in grid:
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continue
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count[n] += 1
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if n in dist:
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continue
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dist[n] = cost
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i, j = n
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d = grid[n]
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if d&N: push(i-1,j,S)
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if d&S: push(i+1,j,N)
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if d&W: push(i,j-1,E)
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if d&E: push(i,j+1,W)
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#print(count.values())
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if not all(c == 2 for c in count.values()):
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# not a loop
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return {}
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return dist
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for D in [W|S, N|W, N|E, S|E, N|S, W|E]:
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grid[start] = D
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loop = find_loop(grid, start)
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if loop:
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print(D, loop)
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print(max(loop.values()))
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